China’s ethnically Korean citizens in the Yanbian borderland underwent language suppression during the era of high socialism, driven by a sweeping vocabulary of Maoist social utopianism. As China’s ‘leading ethnic group’, the revolutionary Han undertook an ‘Anti-Local Nationalism’ campaign denunciation advising that ethnic Koreans learn Chinese for their own good, and with the Great Leap Forward campaign the full-blown theory of materialism was applied to linguistic assimilation. The Korean language was relegated to a conceptual category of ‘superstructure’, while labor efficiency posed Korean itself as a barrier and undermined ethnic Korean attainments in economy and education. This study demonstrates evidentiary weaknesses in the era’s prevailing political theory and identifies ideological fault lines under China’s ethnic language policies.